Re: [PATCH 3/4] gnu: libcanberra: Add propagated-input.

[Federico Beffa <beffa@ieee.org>]

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On Thu, Jan 8, 2015 at 9:39 PM, Ludovic Courtès <ludo@gnu.org> wrote:
> That said, this kind of patch is not very different from the automated
> shebang patching that we do, IMO.

I do not see it this way because the shebang concept is fully
standardized, while here we are patching a "random" piece of code.

> The reason I’m not thrilled by the use of ‘propagated-inputs’ here is
> that that’s not what they were designed for at the beginning.
>
> It may also lead to usability problems.  Remember that when A is a
> propagated input of B, installing B in a profile also installs A in that
> profile.  So, if each GTKish package propagates sound-theme-freedesktop,
> then installing several such packages in the same profile is likely to
> lead to collisions just because the themes differ (those collisions may
> be harmless, but they will at least trigger a bunch of warnings every
> time the user operates on their profile, which is not desirable.)

Thanks for explaining your concern. But doesn't this problem exist
with most uses of propagated-inputs? As one example libssh2 propagates
libgcrypt. If the user installs a different version of libgcrypt (with
a possibly different ABI), doesn't this causes problems (required
version not found, or worse)?

In any case I've updated libcanberra with a patch to find the default
sounds without the need for propagated-inputs. Differently from your
suggested patch I'm proposing to add the default sounds store
directory to the code dealing with XDG_DATA_DIRS. This is because
XDG_DATA_HOME can only be a single directory and is inspected first.
XDG_DATA_DIRS can list an arbitrary number of directories and is only
inspected later. This is designed to allows the user to modify any
theme at his pleasure.

Regards,
Fede

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From a1d7a5b9ed1392d8c5c1a8561357b72e48253ccf Mon Sep 17 00:00:00 2001
From: Federico Beffa <beffa@fbengineering.ch>
Date: Thu, 18 Dec 2014 21:32:34 +0100
Subject: [PATCH 3/4] gnu: libcanberra: Add default sounds support.

* gnu/packages/libcanberra.scm (libcanberra): Add input
  'sound-theme-freedesktop'.  Add phase 'patch-default-sounds-directory to
  patch the default sounds directory.
---
 gnu/packages/libcanberra.scm | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/gnu/packages/libcanberra.scm b/gnu/packages/libcanberra.scm
index 764c327..91760d8 100644
--- a/gnu/packages/libcanberra.scm
+++ b/gnu/packages/libcanberra.scm
@@ -55,9 +55,36 @@
        ("libtool" ,libtool)
        ("libvorbis" ,libvorbis)
        ("pulseaudio" ,pulseaudio)
-       ("udev" ,eudev)))
+       ("udev" ,eudev)
+       ("sound-theme-freedesktop" ,sound-theme-freedesktop)))
     (native-inputs
      `(("pkg-config" ,pkg-config)))
+    ;; "sound-theme-freedesktop" is the default and fall-back sound theme for
+    ;; XDG desktops and should always be present.
+    ;; http://www.freedesktop.org/wiki/Specifications/sound-theme-spec/
+    ;; We make sure libcanberra will find it.
+    (arguments
+     `(#:phases 
+       (alist-cons-before
+        'build 'patch-default-sounds-directory
+        (lambda* (#:key inputs #:allow-other-keys)
+          (let ((sounds (string-append
+                         (assoc-ref inputs "sound-theme-freedesktop")
+                         "/share")))
+            (substitute* "src/sound-theme-spec.c"
+              (("return \"/usr/local/share:/usr/share\";")
+               (string-append "return \"" sounds "\";\n"
+                              "             else {\n"
+                              "                const char *stp = \":"
+                              sounds "\";\n"
+                              "                size_t len =  strlen(stp) + "
+                              "strlen(g) + 1;\n"
+                              "                "
+                              "char *g2 = (char*) malloc(len);\n"
+                              "                return "
+                              "strcat(strcpy(g2, g), stp);\n"
+                              "        }")))))
+          %standard-phases)))
     (home-page "http://0pointer.de/lennart/projects/libcanberra/")
     (synopsis
      "Implementation of the XDG Sound Theme and Name Specifications")
-- 
1.8.4